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Carbon‐13 NMR chemical shift substituent effects 8 —3‐monosubstituted 2‐methylpropenes
Author(s) -
Rittner Roberto,
Braibante Mara E. F.
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260300513
Subject(s) - chemistry , chemical shift , methylene , heteroatom , steric effects , intramolecular force , electronic effect , substituent , computational chemistry , carbon 13 nmr , carbon fibers , stereochemistry , photochemistry , medicinal chemistry , organic chemistry , ring (chemistry) , materials science , composite number , composite material
13 C NMR chemical shifts for some 3‐heterosubstituted 2‐methylpropenes are reported. The α‐methylene chemical shifts show excellent linear correlations with the corresponding data for some substituted carbonyl compounds (propanones, methyl acetates and N , N ‐diethylacetamides). Their estimated intramolecular interaction shifts are indicative of electronic interactions between the heteroatom and the ethylenic double bond. The sp 2 carbon shifts calculated by Dorman et al. 's method, taking a proposed set of β σ and β π parameters, are in close agreement with the experimental values. Neither the α‐methylene nor the olefinic carbon chemical shifts correlate well with the usual electronic and steric parameters of the substituents.